canactair
chaiienQer
OPERATING MANUAL
PSP 606
L AND R ACU FAIL LIGHTS
Amber FAIL light comes on:
- When overpressure occurs between primary heat
exchanger and compressor section of cold air unit.
- When air supply from cold air unit to secondary
heat exchanger in associated ACU overheats.
- On aircraft incorporating Canadair Service Bulletin
600-0476, FAIL light comes on if switch/light is
pressed out (ACU off) and ACU pressure regulator
and shutoff valve fails open.
CKPT HEAT SWITCH
Three-position switch controls supply of engine
bleed air to footwarmer and demist system.
NORM — Right pressure regulator shutoff valve
is open.
L AND R ACU OFF SWITCH/LIGHTS
Control flow of engine bleed air to the
air conditioning units.
When pressed in, associated pressure
regulator and shutoff valve opens and white
OFF light goes out.
When pressed out, associated pressure
regulator and shutoff valve closes and OFF
light comes on.
STBY — Left pressure regulator shutoff valve
is open.
OFF — Both pressure regulator shutoff valves
are closed.
ISOL OPEN SWITCH/LIGHT
Controls upper bleed air isolator valve to isolate
ACU No. 1 from ACU No. 2.
When pressed in, upper bleed air isolator valve
opens and green OPEN light comes on.
When pressed out, upper bleed air isolator valve
closes and light goes out.
L ENG AND R ENG BLEED CLOSED SWITCH/LIGHTS
Control the flow of engine bleed air from associated
engine into the bleed air manifold.
Bleed Air Control Panel
Figure 4 SECTION 2
Page 9
Feb 12/88
canadair
chanencjer
OPERATING MANUAL
PSP 606
E. Temperature Control (Figure 5)
The cabin and flight compartment temperatures are controlled by separate
control systems. One system monitors and controls the cabin temperature
through ACU No. 2; the other system monitors and controls the flight
compartment temperature through ACU No. 1. The temperatures are selected
by operation of individual controls located on the temperature control
panel in the flight compartment.
The temperature control panel contains two, three-position mode selector
switches, marked NORMAL, STANDBY and MAN, and two temperature control
switches. One selector switch and control switch are used for cabin
control and the remaining two for flight compartment control. When the
selector switch is in the NORMAL position, the control is fully automatic
and uses a fan/sensor to measure the temperature in the cabin or flight
compartment with reference to the temperature control switch. The
temperature sensed by the fan/sensor is fed to an electronic temperature
controller which also receives signals from a duct temperature sensor and
the TEMPERATURE CONTROL panel. If a difference exists between the
temperatures, the temperature controller causes an electromagnetic control
valve to vary the amount of servo pressure delivered to the temperature
control modulating valve which mixes precooled and cold air to produce the
desired conditioned air temperature. When the desired and selected
compartment temperatures are equal, the temperature controller returns the
temperature control modulating valve to a mid position to maintain a steady
temperature.
When the temperature control switch is in the STANDBY position, the control
is still fully automatic but only the temperature sensed by the duct
sensors is fed to the temperature controller. The temperature controller
uses this signal together with the temperature selected on the temperature
control panel to operate the temperature control modulating valve.
When the temperature control switch is in the MAN position, the automatic
control facility is de-activated. Control of the temperature control
modulating valve is determined by the position of the temperature selector
switch on the temperature control panel.
The STANDBY and MAN modes are regarded as alternate modes of operation and
are used in the event of a malfunction in the NORMAL mode of operation.
A temperature limiter reduces the temperature of the air in the conditioned
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